Abstract: A system and process for generating, on-site, a sustained C6+C7 aromatic rich solvent stream for tar solvation within the olefin plant employing a two-fuel oil tower system receiving a hydrocarbon feed from a quench water separator drum, where the two-fuel oil tower system is configured to make a sufficient solvent stream containing C6+C7 aromatic rich hydrocarbons that is recycled and mixed with quench water going to the quench water separator drum to assist in removing tar molecules out of the quench water.

Abstract: A drilling and thread forming fastener is provided having a threaded shank and a pilot end. The fastener pilot end in cross section has a major and minor axis intersecting at the fastener center of rotation. A pair of arcuate flutes are disposed in opposed quadrants from a pair of arcuate lands, each of said arcuate flutes and an arcuate land intersecting on the major axis to form a cutting edge of the fastener, the two cutting edges being disposed in a plane containing the center of rotation of the fastener.The fastener construction is adaptable to applications in relatively thick materials including cement or cinder block, and is effective to increase tool life when manufactured by a forging process.

Abstract: This disclosure concerns a light gauge self-tapping sheet metal screw having a threaded shank and cap-type head, which head has a tool-engaging surface. Between the cupped recess of the head and the shank are a plurality of pyramidal ribs that extend partway around the shank for deforming the edge of the holes in the sheet metal up against the recessed surface of the cup of the head to increase the stripping and backout torque of the screw.

Abstract: A fastener for attaching sheet metal or articles to sheet metal. The fastener is a self-locking sheet metal screw having a plurality of equally spaced teeth formed within a recess beneath the fastener head during the heading operation. The teeth preferably have curved trailing edges and straight or slightly inclined leading edges, and each extends laterally a different distance from the shank, as well as vertically a different distance along the shank, such lateral and vertical distances on a single tooth being equal.